Firing simulator

ABSTRACT

The present invention concerns a simulator arranged for the simulation of firing, which simulator is intended to be mounted on a weapon with aiming means. The simulator contains an emitter for a simulation bean and an emitting device for an alignment beam, which device contains a reticle arranged in a first focal plane of an optical system. The optical system is characterized in that it contains means for beam-splitting, where the optical system has a second focal plane, and where the emitter for the simulation beam is arranged in an optical path or extension thereof containing the second focal plane.

TECHNICAL AREA

[0001] The invention concerns simulators for simulating firing. Thesimulators are intended to be mounted on a weapon with a sight.

STATE OF THE ART

[0002] During simulated firing, the simulator emits a laser beam orelectromagnetic radiation generated by means of a technology other thanlaser technology. The beam can be detected by one or more detectorsmounted on one or more targets. The emitted beam, e.g. the laser beam,exhibits different intensity in different directions of radiation, whichare known collectively as the “laser lobe”. When the irradiance from thelaser lobe at a given distance and in a given direction from the emitterexceeds the detection level of any detector on the target, the simulatedeffect of a weapon being fired at the target system located in saiddirection and at said distance is obtained.

[0003] WO00/53993 describes a device and a method for simulating thefiring of a weapon. The simulated firing is accomplished using asimulator mounted on a weapon with a sight. The simulator is arranged soas to emit an electromagnetic simulation beam outward along a simulationaxis. The simulator is also arranged so as to emit a visible alignmentbeam along an alignment axis that forms a fixed and known angle to theaforementioned simulation axis. The simulator contains adjusting meansfor collectively controlling the two aforementioned axes, the simulationaxis and the alignment axis, so that they maintain their mutual fixedand known angtilar relation during the adjustment. The alignment beam ismade visible in the weapon sight by means of a reflecting device,whereupon the alignment beam generates an aiming mark which, when it isobserved in the weapon sight, indicates the misalignment between thesimulation axis and the sight. This makes it possible for the marksmanto align the sight with the simulation axis in a simple way, using theadjusting means.

[0004] Both the simulation beam and the alignment beam are generated bya common optical system, so that the simulator will function in a stablemanner. A laser emitter is used to generate the simulation beam, whichlaser emitter is placed in the focal plane of the optical system. Areticle which, when illuminated, generates the alignment beam, is placedin the same focal plane as the laser. The laser and the reticle are alsoin fixed mechanical connection with one another.

[0005] This yields an extremely robust and stable system, but onedisadvantage is that the reticle interferes with the simulation beam.

DESCRIPTION OF THE INVENTION

[0006] One purpose of the present invention is to provide a firingsimulator that is a considerable improvement over the prior art, andwhich enables the simulation beam from the simulator to be given to anoptimum intensity distribution.

[0007] This has been achieved by means of a simulator arranged tosimulate firing, which simulator is intended to be mounted on a weaponwith aiming means. The simulator contains an emitter to emit asimulation beam outward along a simulation axis, and an emitting devicefor emitting an alignment beam outward along an alignment axis, wherethe emitting device for the simulation beam includes a reticle arrangedprimarily in a first focal plane of an optical system. The simulator ischaracterized in that the optical system contains means for beamsplitting, whereupon the optical system has a second focal plane. Theemitter for the simulation beam is then arranged in an optical path orextension thereof that encompasses the second focal plane.

[0008] In one embodiment the transmittance and reflectance of thebeam-splitting means are wavelength-dependent, and thus different forthe simulation beam and the alignment beam.

[0009] With the emitter of the simulation beam physically separated fromthe emitter of the alignment beam, the components for generating thealignment beam do not interfere with the simulation beam. As a result,the simulation bean can be given an optimal intensity distribution (lobeshape).

[0010] In order to shape the beam lobe of the simulation beam so as tobetter accord with the probability that a detector at a target willdetect a hit when live ammunition is used, beam-shaping means in oneembodiment are arranged in the beam path of the simulation beam. Thebeam-shaping means are arranged so as to shape the beam in such a waythat the beam lobe has an essentially constant diameter within a largerange of distances from a given minimum distance from the simulator upto primarily a maximum range for the simulation beam. The given minimumdistance is characteristically 5-10 meters from the emitter for thesimulation beam.

[0011] The beam-shaping means may include optical components, but mayalso include other types of devices for modulating electromagneticradiation.

[0012] Preferred embodiments may exhibit one or more of the featuresspecified in the dependent claims.

FIGURE DESCRIPTION

[0013]FIG. 1 illustrates a simulator on a weapon where the aiming axis,simulation axis and alignment axis are indicated.

[0014]FIG. 2 shows an example of an optical system in the simulator.

[0015]FIG. 3 shows an alternative example of an optical system in thesimulator.

[0016]FIG. 4 shows yet another example of an alternative optical systemin the simulator.

[0017]FIG. 5 schematically depicts the criteria for an ideal lobe shapefor a simulation beam in accordance with one embodiment of thesimulator.

[0018]FIG. 6 illustrates an example of a method for calculating anessentially aspherical surface.

[0019]FIG. 7 shows an example of a conformation of a diffractivesurface.

DESCRIPTION OF EMBODIMENTS

[0020] In FIG. 1 a simulator 1 is mounted on a weapon 2 equipped withaiming means 3, preferably in the form of a sight. In the simulator 1there is generated a simulation beam along a simulation axis 5. Thesimulator also emits an alignment beam along an alignment axis 7 that isparallel to the simulation axis 5. The aiming means 3 of the weapondefine an aiming axis 8, and it is this aiming axis that defines thedirection in which a round will leave the weapon 2 when live ammunitionis fired.

[0021] In FIG. 2 the simulation beam is generated in an optical system12 by a laser emitter 4 in the form of, e.g. a laser diode whosewavelength is, e.g. roughly 900 mm. It is also conceivable that theemitter could emit electromagnetic radiation using some technology otherthan laser technology. To improve the circular symmetry of thesimulation beam from the laser diode, an optical fiber whose diametercan be roughly 50 μm is used in one embodiment (not shown), which fiberis arranged in the beam path after the laser diode in close relation tothe laser diode so that the beam is reflected a number of times insidethe fiber, thereby achieving a more symmetrical distribution of theaiming.

[0022] There is arranged in the beam path from the laser diode abeam-shaping optical component 6 with essentially positive refractivepower containing at least one diffractive transmitting surface oraspherical refractive surface. There is arranged after the opticalcomponent 6 in the beam path a beam splitter 9 whose beam-splittinglayer 10 is arranged so as to reflect a significant part of thesimulation beam toward a projection lens 11. The optical component 6 ispositioned in relation to the projection lens 11 and the laser diode 4in such a way that the focal plane 13 of the projecting lens along thisoptical path with reflection in the beam-splitting layer 10 lies at thepoint where the simulation beam from the optical component 6 has adesired lobe shape, as will be described in detail below.

[0023] A source of visible light 14, such as a light-emitting diode, isarranged to generate the alignment beam. The light source 14 is arrangedso that it illuminates a reticle 15 in the form of e.g. a glass platewith an engraved or imprinted pattern, cross-hairs or the like. Thereticle is in turn arranged in a focal plane 16 of the projection lensin an optical path that passes through the beam-splitting layer 10 ofthe beam splitter 9. A portion of the alignment beam passes through thebeam-splitting layer, while a second part is reflected away from theoptical system 12. In the embodiment shown in FIG. 2 the laser diode 4,the light source 14 and the beam splitter 9 are placed in relation toone another in such a way that both the simulation beam and thealignment beam strike the beam-splitting layer 10, and in such a waythat the reflected simulation beam and the alignment beam that passedthrough the beam-splitting layer pass as a composite beam toward theprojection lens 11. After passing through the projection lens 11, thesimulation beam and the alignment beam leave the simulator 1 along acommon simulation and alignment axis, 5, 7.

[0024] The technology involved in designing a beam splitter with theforegoing properties is conventional to one skilled in the art. It iscurrently possible to design, at reasonable cost, a beam-splitting layerthat reflects roughly 90% of the beam in a wavelength range in which thesimulation beam exists while 10% passes through the layer and out fromthe optical system 12, and while the beam splitter simultaneously allowsroughly 75% of the visible alignment beam to pass through. It should beadded that it is not critical to the performance of the optical system12 for an extremely high proportion of the beam to be passed to theprojection lens. A somewhat lower portion can be compensated for byincreasing the output power from the laser diode 4 and the light source14.

[0025] In an alternative embodiment the placements of the focal planes16, 18 are reversed so that the beam-splitting layer allows thesimulation beam to pass in the direction toward the projection lens andreflects the alignment beam toward the projection lens.

[0026] The simulation beam is generated by the laser diode in FIG. 3 aswell. There is arranged in the beam path from the laser diode abeam-shaping optical component 17 with essentially negative refractivepower containing at least one diffractive transmitting surface oraspherical refractive surface. After the negative optical component 17there is arranged in the beam path a beam splitter 9 whosebeam-splitting layer 10 is arranged in the same manner as describedabove so as to reflect a significant part of the simulation beam towardthe projection lens 11. The negative optical component 17 is placed inrelation to the projection lens 11 and the laser diode 4 in such a waythat a virtual focal plan 18 in the extension of the optical path liesat the point where the simulation beam from the optical component shouldhave a desired lobe shape, as will be described in detail below. Thisembodiment too includes the alignment-beam-generating light source 14arranged so that it illuminates the reticle 15. The reticle is arrangedin the focal plane 16 of the projection lens 11 in an optical paththrough the beam-splitting layer of the beam splitter. A first portionof the alignment beam passes through the beam-splitting layer and towardthe projection lens 11, while a second part is reflected away from theoptical system 12. In this embodiment the laser diode 4, the lightsource 14 and the beam splitter 9 are again placed in relation to oneanother in such a way that both the simulation beam and the alignmentbeam strike the beam-splitting layer, and in such a way that thereflected simulation bean and the alignment beam that passed through thebeam-splitting layer pass toward the projection lens 11 as a compositebeam. The function of this embodiment is thus identical with that of theembodiment depicted in FIG. 2. In one example the mechanical dimensionsof the beam splitter in the embodiment shown in FIG. 3 are such that,with the reticle and the beam-shaping optical component 17 arranged atthe beam splitter, by means of e.g. gluing, the necessary opticaldistance is achieved in the optical system. This yields an extremelyrobust design. For a more compact design, one or more further reflectingsurfaces may be included.

[0027] In an alternative embodiment the placements of the focal planes16, 18 are reversed so that the beam-splitting layer allows thesimulation beam to pass in the direction toward the projection lens andreflects the alignment beam toward the projection lens.

[0028]FIG. 4 includes the light source 14, the reticle 15 arranged inthe focal plane 16 of the projection lens 11, and the beam splitter 9.The light source 14 generates the alignment beam, which is allowed topass through the reticle 15, the beam splitter 9 and the projection lens11 in the same manner as described above. The laser diode 4 forgenerating the simulation beam is arranged in relation to the othercomponents in such a way that the simulation beam is allowed to passonce through the beam-splitting layer 10 before the beam reaches anessentially positive or negative optical component 19 in the form of atleast one diffractive or aspherical reflecting surface. The simulationbeam is reflected from this optical component 19 back to the beamsplitter, where a portion of the simulation beam is reflected toward theprojection lens as described above. Reference number 20 designates avirtual focal plan for the projection lens in an optical path withreflection in the beam splitter. The function of this embodiment isexactly the same as in those illustrated in connection with FIGS. 2 and3. In an alternative embodiment the placements of the focal planes 16,18 are reversed so that the beam-splitting layer allows the simulationbeam to pass in the direction toward the projection lens and reflectsthe alignment beam toward the projection lens.

[0029] The optical component 6, 17, 19 in each described embodiment isdesigned so that the beam lobe of the simulation beam will, as the beamleaves the projection lens 11 in the simulator 1, have an essentiallycircular cross-section 21 along its entire length. Further, the diametershall be substantially constant along the entire length from a distanceR_(min) located roughly 5 to 10 meters from the simulator out to amaximum range R_(max) which, for various applications, is usuallybetween 300 m to 1200 m from the simulator, as shown in FIG. 5. Theconstant diameter is characteristically 0.3 m to 1.0 m and preferablyabout 0.5 m in an application where the target is an infantry soldier.

[0030] The intensity of this ideal lobe is thus defined by the followingequation, where the distance R_(i) is a distance from the simulatoralong the simulation axis 5, and R_(min)<R_(i)<R_(max):

I(R _(i))=E _(τ) *R ² _(i) {square root}T(R _(i)) for α(R _(i))=r/Ri,yielding a function I(α), where

[0031] E_(τ) is the detection threshold of the target,

[0032] T(R_(i)) is the atmospheric transmittance for a chosen weathersituation,

[0033] α(R_(i)) is the radial angle from the symmetry axis of the beamlobe (=the simulation axis 5) for

[0034] which the intensity is I(R_(i)), and

[0035] r is one-half the diameter of the target surface, taking intoaccount the placement of one or more simulation-beam-detecting detectorson the target.

[0036] A power distribution E(α) is then obtained as E(α)=I(α)/(τ×f²) ifthe beam splitter transmits the beam from this focal plane toward theprojection lens, or as E(α)=I(α)/(ρ*f²) if the beam splitter reflectsthe beam from the focal plane, where f is the effective focal length ofthe optical system and τ and ρ are the product of the transmittance ofthe optical system and the transmittance and reflectance of the beamsplitter, respectively.

[0037] The radiation power P that passes the second focal plan via asubsurface with a radius y centered about the optical axis is theintegral from 0 to y/f of (E(α)*2*π*α*dα).

[0038] The radiation power P_(s) that passes the diffractive/asphericalsurface via a subsurface with the radius x centered about the opticalaxis is the integral from 0 to x/a of (I_(s)(Θ)*2*π*Θ*dΘ), whereI_(s)(Θ) is the radiation intensity from the laser diode in a directionthat forms the angle Θ with the optical axis, and were a is the distancebetween the laser diode and the diffractive/aspherical surface. The beamfrom the laser diode or from the optical fiber is assumed to beapproximately rotationally symmetric within a limited angular range nearthe optical axis.

[0039] By setting P_(s)=P and letting x rise from 0 (=the optical axis),the slope dz/dx for an aspherical surface between two media withdifferent refractive indices n₁ and n₂ can be calculated for each pointat the distance x from the optical axis by applying the law ofrefraction, n₁*sin(β₁)=n₂* sin(β₂) and the formula y=Θ*(a+b)−b*(β₁-β₂).The height of the surface measured parallel to the optical axis z(x) isobtained by integrating the slope; see FIG. 6.

[0040] For a diffractive surface between two media with refractiveindices n₁ and n₂ the phase function φ(x)=z(x)*2*π*(n₁-n₂)/λ isobtained, where λ is the wavelength of the beam.

[0041] If the diffractive surface is given a form as per FIG. 7(kinoform), then all orders except for first order diffraction will besuppressed.

[0042] We have now described a number of types of optical componentsthat can be used to create a desired lobe shape, and how the opticalcomponents must generally be conformed to obtain the desired simulationbeam lobe properties. In an alternative embodiment the optical componentis replaced with a beam-reshaping device of an alternative type arrangedso as to modulate the simulation beam to produce the desired beam lobeshape.

[0043] It is possible to incorporate diffractive or asphericalrefractive optical components in, e.g. a firing simulator such as isdescribed in WO00/53993 to shape the simulation beam so that it has alobe whose diameter is essentially constant along a section of thesimulation axis from a given distance R_(min) from the simulator out toa maximum range R_(max).

1. A simulator arranged for simulating firing and intended to be mountedon a weapon with aiming means, which simulator includes an emitter for asimulation beam and an emitting device for an alignment beam, whichdevice includes a reticle arranged in a first focal plane of an opticalsystem, characterized in that the optical system contains means for beamsplitting, whereby the optical system has a second focal plan.
 2. Asimulator according to claim 1, characterized in that the emitter forthe simulation beam is arranged in an optical path or extension thereofencompassing the second focal plane.
 3. A simulator according to claim2, characterized in that the transmittance and reflectance of thebeam-splitting means are wavelength-dependent.
 4. A simulator accordingto claim 1, characterized in that the simulation beam iselectromagnetic, and in that the emitter of the simulation beam is alaser diode.
 5. A simulator according to claim 1, characterized in thatan optical fiber is arranged in close relation to the emitter for thesimulation beaming the beam path after the emitter.
 6. A simulatoraccording to claim 1, characterized in that the means are arranged inthe beam path of the simulation beam to shape the beam so that its beamlobe exhibits a predetermined shape within a large range of distancesfrom a given minimum distance (R_(min)) from the simulator principallyout to a maximum range (R_(max)) for the simulation beam.
 7. A simulatoraccording to claim 6, characterized in that the beam lobe has anessentially constant diameter within the range of distances.
 8. Asimulator according to claim 6 or 7, characterized in that thebeam-shaping means contain an optical component.
 9. A simulatoraccording to claim 8, characterized in that the optical componentcontains at least one diffractive transmitting surface.
 10. A simulatoraccording to claim 8, characterized in that the optical componentcontains at least one diffractive reflecting surface.
 11. A simulatoraccording to claim 8, characterized in that the optical componentcontains at least one aspherical refractive surface.
 12. A simulatoraccording to claim 8, characterized in that the optical componentcontains at least one aspherical reflective surface.
 13. A simulatoraccording to claim 8, characterized in that the conformation of theoptical component is chosen based on geometrical optics calculations.14. A simulator according to claim 9 or 10, characterized in that theconformation of the optical component is chosen based on Fouriertransform calculations.